Fertilizer knives have been in use for many years and in recent years, with increasing popularity of minimum tillage types of planting systems, fertilizer knives have been attached to planters for the purpose of adding enough fertilizer adjacent to the seed to give the plant food for getting a good start. Ideally, the fertilizer should be placed about two inches to one side or two inches below the seed. If too much fertilizer is placed to near the seed bed, it will take water away from the seed or roots resulting in the well-known "fertilizer burn" phenomenon and poor germination.
In prior art systems typically, the fertilizer knife has a fixed depth and is fixed laterally as well. The problem with this fixed type of an arrangement is that placement of the starter fertilizer at the proper distance from the seed bed is not always achieved and may need adjustment. Also, when the rows are not precisely straight, then the fertilizer knife, if fixed, will tend to place the fertilizer too far to one side or the other when operatively attached to a rigid tool bar portion of the planter. Consequently, there is a need for a new fertilizer knife which has enough versatility to permit adjustment of the depth, to permit lateral adjustment, and to cause the knife to track more precisely at the set distance from the seed bed.